As disclosed in U.S. Pat. No. 9,167,275, the entire disclosure of which is incorporated herein by reference, computer-implemented systems and methods provide for the autonomous broadcasting of video data, audio data, or video and audio data during an event, wherein the broadcasting can be scheduled in advance and from a remote location (i.e., over a network). Various conventional protocols, such as Real-time Transport Protocol (RTP) over User Datagram Protocol (UDP), are used for sending the data over the network.
The systems and methods often use the H.264 video compression standard for video encoding and the Advanced Audio Coding (AAC) audio compression standard for audio encoding. These compression standards are designed to ride through some amount of packet loss. Consequently, UDP is preferred to Transmission Control Protocol (TCP), as TCP's congestion avoidance mechanisms can cause large backlogs (and subsequent buffering) in the face of occasional packet loss. Thus, RTP over UDP is frequently used as a backhaul protocol in the systems and methods.
Although RTP over UDP achieves the goals of having lower latency and less buffering than TCP, customers do notice packet losses, as artifacts commonly become visible/audible in the decoded picture and sound, especially when losses are part of a keyframe. Packet loss generally comes in two forms: (1) loss due to available bandwidth being lower than the transmitted data, and (2) loss due to temporary congestion along the backhaul path. A redesigned backhaul protocol would ideally address both of these situations, for example, by: (1) observing backpressure from the backhaul link and communicating that upstream to allow higher-level software to adjust transmission rates and (2) using measures to ensure that, in most circumstances, occasional loss is recovered.
Furthermore, the use of RTP over UDP allows intermediary backhaul nodes to freely inspect and analyze packet contents. This means that the stream data is free to be intercepted, observed, and even modified by any third-party through which the content passes, which may be undesirable for certain broadcasters with sensitive content. This also means that those intermediate nodes may use that information for undesired packet shaping or outright filtering. Service providers have used this approach to impose size restrictions on data transfers, including the streaming of video and/or audio data. A redesigned backhaul protocol should prevent or otherwise increase the difficulty of performing such activities.
Further still, the use of RTP over UDP leaves the distribution network vulnerable to attack at ingress by attackers who may spoof streamed content. Since the media servers are not able to ensure that received data actually originated from the expected transmission device, an attacker would be able to stream their own RTP/UDP data to the media server and disrupt the stream or even inject their own content. A redesigned backhaul protocol should prevent or otherwise increase the difficulty of performing such activities.
In view of the above, there is an unmet need for an improved backhaul protocol for the transmission of video and audio data.